1. Field of the Invention
The invention herein disclosed is a multipurpose tool for use in the field of earth boring. It is a tool designed to be installed in a drilling string to selectively enable various forces to be applied to the drill bit without having to pull the drill string (“trip the pipe”) from the hole. Namely by varying the amount and direction of vertical forces applied to the drill string the operator of the drilling rig can selectively cause the tool of the present invention to apply torque or a combination of torque and vibratory impacts either (as selected) downwardly or upwardly.
2. Description of Related Art
In the field of earth boring various earth formations, some relatively easy to drill and some relatively difficult to drill are encountered. In some of these earth formations application of weight and rotary forces to the drill bit is sufficient to cause drilling to proceed at an acceptable rate. However with respect to certain formations a greater rate of penetration can be achieved by a combination of weight, rotary forces and vibratory impacts is applied to the drill bit. It is therefore desirable to be able to selectively chose whether drilling of a particular formation might be best achieved with only weight and torque or a combination of weight, torque and vibratory impacts should be employed. It would be undesirable (both expensive and time consuming) to be required to pull the drill string from the hole (“trip the pipe”) in order to manually, at the surface of the earth, install or shift some apparatus, in order to shift between said drilling modes. The tool of the present invention allows drilling operations to be shifted between said drilling modes without having to pull the drill string from the hole. By increasing weight on bit the tool of the present invention shifts into a mode which transmits weight, torque and vibratory impacts down-hole (ultimately to the bit at the bottom of the hole).
Not only in the field of drilling are various earth formations encountered (therefore making it desirable, during drilling ahead operations, to be able to selectively shift between the modes indicated above) at times drilling ahead may not be able to proceed because the bit becomes stuck. In such cases application of vibratory forces, sometimes downward, sometimes upward, sometimes alternatively working the drill pipe upward and downward while applying vibratory forces to the bit may be able to free the bit and allow drilling to proceed ahead. The tool of the present invention allows for the selective application of rotary, or a combination of rotary and vibratory impacts to be applied in the upward or downward (as selected direction) therefore is useful in freeing stuck bits.
So far as applicant is aware prior art does not disclose a tool that may be shifted between all four modes, namely a “weight and torque” mode, a “weight, torque and vibratory impacts” mode, a “lifting and torque” mode and a “lifting, torque and vibratory impact” mode, without being required to trip the drill pipe from the hole.